Method and system for operating a portable electronic device in a power-limited manner

ABSTRACT

Improved techniques to manage operation of a portable electronic device having a substantially depleted battery when power is available from an external, power-limited source are disclosed. In one embodiment of the invention, the substantially depleted battery can be initially charged while a power-intensive operation is delayed. Once the battery has adequate charge to assist the external, power-limited source in powering the portable electronic device, the power-intensive operation can be performed. In this manner, power consumption of a portable electronic device can be managed so that reliable operation is achieved without exceeding limits on power being drawn from an external, power-limited source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority under 35U.S.C. § 120 to U.S. application Ser. No. 12/400,670, filed Mar. 9,2009, now U.S. Pat. No. 7,746,032, issued Jun. 29, 2010, which is acontinuation of and claims priority to U.S. application Ser. No.11/009,675 filed Dec. 10, 2004, now U.S. Pat. No. 7,541,776, issued Jun.2, 2009, each of which are hereby incorporated by reference herein.

This application is related to: (i) U.S. patent application Ser. No.10/961,776, filed Oct. 8, 2004, and entitled “METHOD AND SYSTEM FORDISCOVERING A POWER SOURCE ON A PERIPHERAL BUS,” and which is herebyincorporated by reference herein; and (ii) U.S. patent application Ser.No. 10/961,571, filed Oct. 8, 2004, and entitled “METHOD AND SYSTEM FORTRANSFERRING DATA WITH RESPECT TO A PORTABLE ELECTRONIC DEVICE,” andwhich is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to portable electronic devices and, moreparticularly, to power-limited operation of portable electronic devices,such as portable media players.

2. Description of the Related Art

A media player is normally portable media device that isbattery-powered. A media player typically operates to store and playmedia items for the benefit of its user. One exemplary media player isthe iPod® offered by Apple Inc. of Cupertino, Calif. which has thecapability to store and play many different media items (i.e., songs) aswell as synchronize its media items with a host computer via a busconnection.

When the media player is connected to a host computer by a busconnection over a cable, power can also be supplied to the media playerby way of the cable. For example, when the bus connection is a FIREWIREconnection or a Universal Serial Bus (USB) connection, power isavailable to be supplied to the media player over the bus connection.However, the available power from the bus connection is typicallylimited by the associated bus standard. For example, USB specificationlimits the amount of power drawn from a USB bus, normally, the powerlimit in terms of current is 100 mA. The available power from the busconnection can be used by the media player to perform variousoperations. Recently, such power from the bus connection has been usedto charge the battery utilized by the media player. However, when themedia player is consuming significant power due to its performance ofoperations, the available power from the bus connection can be exceededby the media player's performance of operations. In such case, thebattery is not able to be charged and can operate in a negative chargeenvironment. In the negative charge environment, the battery's charge isbeing drained because the power consumed by the media player whileperforming various operations exceeds the power available over the busconnection. This is particularly problematic when the battery chargelevel is low. If the battery is not already completely discharged, anegative charge environment might be tolerated for some unknown periodof time. However, if the media player's operations continue, the batterywill eventually be fully drained in which case the media player wouldfail.

Thus, there is a need for improved techniques to manage powerconsumption on a media player so that reliable operation can beachieved.

SUMMARY OF THE INVENTION

Broadly speaking, the invention relates to improved techniques to manageoperation of a portable electronic device having a substantiallydepleted battery when power is available from an external, power-limitedsource. In one embodiment of the invention, the substantially depletedbattery can be initially charged while a power-intensive operation isdelayed. Once the battery has adequate charge to assist the external,power-limited source in powering the portable electronic device, thepower-intensive operation can be performed. In this manner, powerconsumption of a portable electronic device can be managed so thatreliable operation is achieved without exceeding limits on power beingdrawn from an external, power-limited source. As an example, theexternal, power-limited source can be a peripheral bus having data andpower lines.

The invention pertains to portable electronic devices that are poweredby an internal battery and/or a peripheral bus connection with a hostdevice. As examples, the portable electronic devices can be portabledata storage devices (e.g., portable disk drives) or, more particularly,portable media devices. A portable media device, such as a portablemedia player, is typically capable of storing and playing media items aswell as receiving (transferring) media items over a peripheral busconnection with a host device (e.g., personal computer).

The invention can be implemented in numerous ways, including as amethod, system, device, apparatus, or computer readable medium. Severalembodiments of the invention are discussed below.

As a method for starting up a mobile device having a battery, oneembodiment of the invention includes at least the acts of: examining abattery level of the battery; determining whether the battery level issubstantially depleted; determining whether an external, power-limitedpower source is electrically coupled to the mobile device; and deferringstart-up of the mobile device while charging the battery via powerprovided to the mobile device from the external, power-limited powersource when it is determined that the battery level is substantiallydepleted and it is determined that the external, power-limited powersource is electrically coupled to the mobile device.

As a method for starting up a mobile computing device having a battery,another embodiment of the invention includes at least the acts of:examining a battery level of the battery; determining whether thebattery level exceeds a first threshold level; determining whether poweris available from a host computer via a power-limited peripheral buselectrically coupled to the mobile computing device; and initiatingcharging of the battery using at least a portion of the power that isavailable via the power-limited peripheral bus when it is determinedthat the battery level does not exceed the first threshold level and itis determined that power is available from the power-limited peripheralbus.

As a media device, one embodiment of the invention includes at least: amedia store for storing media items; a communication interface forinterfacing with a host device via a cable that provides media data andpower to the media device when the cable is connected between the mediadevice and the host device; a battery for providing power to the mediadevice; and a battery monitor that monitors a battery attribute of thebattery, wherein start-up of the media device is deferred based on thebattery attribute of the battery as monitored by the battery monitor.

As a computer readable medium for performing a power-intensive operationby a mobile device having a battery, one embodiment of the inventionincludes at least: computer program code for examining a battery levelof the battery; computer program code for determining whether thebattery level is substantially depleted; computer program code fordetermining whether a power-limited power source is electrically coupledto the mobile device; and computer program code for deferringperformance of the power-intensive operation by the mobile device whilecharging the battery via power provided to the mobile device from thepower-limited power source when it is determined that the battery levelis substantially depleted and it is determined that the power-limitedpower source is electrically coupled to the mobile device.

Other aspects and advantages of the invention will become apparent fromthe following detailed description taken in conjunction with theaccompanying drawings which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1 is a block diagram of a power management system according to oneembodiment of the invention.

FIG. 2 is a block diagram of an electronic device according to oneembodiment of the invention.

FIG. 3 is a flow diagram of a start-up process according to oneembodiment of the invention.

FIGS. 4A-4C are flow diagrams of a start-up process according to anotherembodiment of the invention.

FIG. 5 is a block diagram of a media player according to one embodimentof the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to improved techniques to manage operation of aportable electronic device having a substantially depleted battery whenpower is available from an external, power-limited source. In oneembodiment of the invention, the substantially depleted battery can beinitially charged while a power-intensive operation is delayed. Once thebattery has adequate charge to assist the external, power-limited sourcein powering the portable electronic device, the power-intensiveoperation can be performed. In this manner, power consumption of aportable electronic device can be managed so that reliable operation isachieved without exceeding limits on power being drawn from an external,power-limited source. As an example, the external, power-limited sourcecan be a peripheral bus having data and power lines.

The invention pertains to portable electronic devices that are poweredby an internal battery and/or a peripheral bus connection with a hostdevice. As examples, the portable electronic devices can be portabledata storage devices (e.g., portable disk drives) or, more particularly,portable media devices. A portable media device, such as a portablemedia player, is typically capable of storing and playing media items aswell as receiving (transferring) media items over a peripheral busconnection with a host device (e.g., personal computer). Although theinvention is further described below with reference to media devices, itshould be understood that the invention is applicable to other types ofportable electronic device besides media devices.

Embodiments of the invention are discussed below with reference to FIGS.1-5. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes as the invention extends beyond these limitedembodiments.

FIG. 1 is a block diagram of a power management system 100 according toone embodiment of the invention. The power management system 100includes an electronic device 102. The electronic device 102 includes,among other things, a battery 104, power consuming circuitry 106, and apower manager 108. The battery 104 provides power for operating theelectronic device 102. For example, the power supplied by the battery104 can be used to power the power consuming circuitry 106 and the powermanager 108. In addition, the electronic device 102 can be coupled to ahost computer 110 by a peripheral cable 112. The host computer 110 has aperipheral connector 114, and the electronic device 102 has a peripheralconnector 116. The peripheral connector 114 can receive a counterpartconnector at one end of a peripheral cable 112, and the peripheralconnector 116 can receive a counterpart connector at another end of theperipheral cable 112. The peripheral cable 112 is used to provide dataand DC power from the host computer 110 to the electronic device 102.Hence, when the peripheral cable 112 is coupled between the hostcomputer 110 and the electronic device 102, the electronic device 102can receive DC power and/or data over the peripheral cable 112. In oneembodiment, a peripheral bus is provided over the peripheral cable 112.As one example, the peripheral bus can be a Universal Serial Bus (USB)bus, and the peripheral connectors 114 and 116 can be USB connectors. Inanother example, the peripheral bus can be a FIREWIRE™ bus, and theperipheral connectors 114 and 116 can be FIREWIRE™ connectors.

The DC power supplied to the electronic device 102 by the peripheralcable 112 can be consumed by various circuitry within the electronicdevice 102. However, the peripheral bus is designed to provide only acertain, limited amount of power to peripheral devices, such as theelectronic device 102. Hence, proper design of the electronic device 102would dictate that the electronic device 102 respect that only acertain, limited amount of power is made available by the peripheralbus. Unfortunately, however, the amount of DC power available from theperipheral bus tends to be insufficient to operate the electronic device102 in many situations. Hence, to prevent the electronic device 102 fromover-consuming the limited amount of available power from the peripheralbus, the electronic device 102 includes the power manager 108. The powermanager 108 can operate the power consuming circuitry 106 within theelectronic device 102 such that the available power from the peripheralbus is not over-consumed. As an example, the power manager 108 candisable, limit or sequence usage of various circuits of the powerconsuming circuitry 106 such that the power being consumed via theperipheral bus is normally not more than the certain, limited amount ofpower made available over the peripheral bus. This allows the electronicdevice 102 to be in compliance with any industry standard that governsthe amount of power that can be drawn from the peripheral bus. Forexample, the peripheral bus can be a USB bus and the electronic device102 can operate in compliance with the power utilization limitationsspecified by the USB specification. The battery 104 provided within theelectronic device 102 can provide power when the peripheral cable 112 isnot connected, or can provide supplemental power (should it be needed)when the peripheral cable 112 is connected. Given that the poweravailable from the peripheral bus is limited, the supplemental poweravailable from the battery 114 can be important and, therefore, shouldbe controlled or limited.

FIG. 2 is a block diagram of an electronic device 200 according to oneembodiment of the invention. The electronic device 200 can, for example,represent the electronic device 102 illustrated in FIG. 1.

The electronic device 200 couples to or includes a peripheral connector202. The peripheral connector 202 is coupled to a DC power (DC PWR)line, a data DP line, a data DM line, and a ground (GND) line. Theselines are supplied to a bus interface 204. The bus interface 204 enablesthe electronic device 200 to receive power and/or participate in datatransmissions and receptions over a peripheral bus. The datatransmissions or receptions can supply data to or receive data fromother power consuming circuitry 206 provided within the electronicdevice 200. Since the invention is primarily concerned with powerutilization at the electronic device 200, the discussion below isprimarily directed to power management at the electronic device 200.

The electronic device 200 also includes a power controller and batterycharger 208 and a battery 210. The power controller and battery charger208 couples to the DC power (DC PWR) line and the ground (GND) line ofthe peripheral connector 202. The power controller and battery charger208 operates to receive DC power from a peripheral cable (i.e.,peripheral bus) via the peripheral connector 202. The power controllerand battery charger 208 also can monitor a battery level for the battery210. Still further, the power controller and battery charger 208 canoperate to charge the battery 210 using some or all of the DC powerprovided by the peripheral cable. The power controller and batterycharger 208 is typically an integrated circuit, such as a standardintegrated circuit (IC) or a custom integrated circuit (e.g., ASIC). Onesuitable integrated circuit suitable for use as the power controller andbattery charger 208 is LTC4055 from Linear Technology Corporation inMilpitas, Calif.

In general, the power controller and battery charger 208 operates tocontrol the operational activity of the electronic device 200 so thatits power draw (e.g., current draw) via the peripheral bus does notexceed the power available according to the industry standard. In thisregard, the power controller and battery charger 208 may cause the businterface 204 or the other power consuming circuitry 206 to deferoperations, sequence operations, or avoid operations so that the powerconsumption of the electronic device 200 is managed. In one embodiment,start-up of the electronic device 200 is deemed to consume more powerthan the available amount of power from the peripheral bus. Hence, insuch an embodiment, the power controller and battery charger 208 ensuresthat the battery 210 is at least charged to a sufficient level such thatduring start-up, the battery 210 can adequately assist the peripheralbus in providing power to the electronic device 200 so that start-up canbe performed.

Typically, the electronic device 200 is a battery-powered device, wherethe battery is rechargeable battery. At least a portion of the poweravailable at the peripheral bus can be used to charge the rechargeablebattery of the electronic device. Hence, the charging operation mayaffect the amount of power available for other circuitry within theelectronic device 200. Furthermore, to the extent that the battery isadequately charged, the battery may offer additional power forconsumption by the electronic device 200 in the event that the availablepower offered via the peripheral bus is exceeded by operational activityof the electronic device 200. Examples of the other power consumingcircuitry 206 will vary widely depending upon implementation.Nevertheless, some examples of other power consuming circuitry 206include a disk drive, a battery charge circuit, a memory device (e.g.,RAM, ROM), a battery monitor, and a display. For example, duringstart-up of the electronic device 200 a disk drive may be repeatedlyaccessed. In such case, since a disk drive often consumes significantamounts of power when being accessed, power consumption tends to be high(e.g., beyond that available from the peripheral bus). The high powerconsumption means that additional power may be needed from the batteryto operate the disk drive. As such, the additional power available fromthe battery is an important consideration for reliable operation of theelectronic device 200, particularly during start-up.

In one embodiment, start-up of the electronic device 200 is a boot-upprocess that initially executes computer instructions resident inrandom-access memory (ROM) (i.e., semiconductor memory) and subsequentlyaccesses a disk drive to obtain other computer instructions that arethen executed. Hence, in such an embodiment, the electronic device 200can perform an initial portion of the boot-up process using power fromthe peripheral bus. However, before permitting a subsequent portion ofthe boot-up process, the power controller and battery charger 208 canensures that the battery 210 is at least charged to a sufficient levelsuch that the battery 210 can adequately assist the peripheral bus inproviding power to complete the subsequent portion of the boot-upprocess.

FIG. 3 is a flow diagram of a start-up process 300 according to oneembodiment of the invention. The start-up process 300 is, for example,performed by an electronic device, such as the electronic device 102illustrated in FIG. 1 or the electronic device 200 illustrated in FIG.2.

The start-up process 300 begins with a decision 302 that determineswhether a start-up request has been made. To be activated, theelectronic device is required to be started-up, e.g., booted-up, as isconventional with various types of computing devices. Typically, thestart-up (or boot-up) process requires retrieving of computer programcode from memory and then executing the computer program code to load anoperating system as well as other utilities, programs, code libraries,etc. When the decision 302 determines that a start-up request has notbeen received, then the start-up process 300 can await such a request.

Once the decision 302 determines that a start-up request has beenreceived, a battery level for the battery of the electronic device isexamined 304. The battery level being examined can pertain to a charge,current, or voltage level of the battery. A decision 306 determineswhether the battery level is adequate. In one embodiment, the batterylevel is adequate if it has sufficient available power to enable theelectronic device to complete its start-up. When the decision 306determines that the battery level is inadequate, then a decision 308determines whether peripheral power is available. For example,peripheral power can be available from a peripheral bus, such as a USB.When the decision 308 determines that peripheral power is available,then the battery is charged 310 using the power made available by theperipheral bus. After the battery has been charged 310 for some periodof time, the start-up process 300 returns to repeat the operation 304and subsequent operations so that the battery level can be reexamined.Alternatively, when the decision 308 determines that peripheral power isnot available, then a low power indication is displayed 312 on a displaydevice associated with the electronic device. The low power indicationcan be represented by text, graphics (e.g., symbols) or both. The lowpower indication serves to inform the user of the electronic device thatstart-up of the electronic device cannot be performed until theelectronic device couples to an external power source, namely, aperipheral bus or power adapter, so that peripheral power becomesavailable.

On the other hand, when the decision 306 determines that the batterylevel is adequate, then start-up of the electronic device can beperformed 314. Consequently, start-up of the electronic device is afterthe battery level is determined to be adequate, which may or may notimpose a delay period while the battery is charged. In the end, thestart-up process 300 operates to ensure safe and reliable start-up ofthe electronic device.

The start up process 300 illustrated in FIG. 3 is most useful in thecase where the battery level of the battery of the electronic device issubstantially depleted when a start-up request is made. With the batterylevel being substantially depleted, the electronic device must becoupled to an external power source, such as a peripheral bus or a poweradapter. Hence, when the electronic device is coupled to a peripheralbus, the electronic device can receive external power over theperipheral bus. However, given that the amount of power drawn onperipheral buses is limited and/or controlled by industry standards, theelectronic device must take care to comply with these standards. If thebattery level is adequate to enable the battery to itself complete astart-up of the electronic device, then the start-up can be performedwithout delay. However, when the battery level is not adequate tostart-up the electronic device, power from the peripheral bus isutilized to initially charge the battery to a limited extent so that itstores adequate charge such that it can supplement the power availableover the peripheral bus during the start-up of the electronic device.

Still further, although not illustrated in FIG. 3, between blocks 302and 304, a decision could be made as to whether a power adapter isavailable to the electronic device. If a power adapter is available,then the start-up process 300 can directly perform the operation 314 soas to start-up the electronic device. On the other hand, when the poweradapter is not available, the operation 304 and subsequent operationsillustrated in FIG. 3 are performed so that, as needed, a degradedbattery can be charged.

FIGS. 4A-4C are flow diagrams of a start-up process 400 according toanother embodiment of the invention. The start-up process 400 is, forexample, performed by an electronic device, such as the electronicdevice 102 illustrated in FIG. 1 or the electronic device 200illustrated in FIG. 2.

The start-up process 400 initially determines whether a softwarestart-up request has been issued. A software start-up request is issuedwhen the electronic device is to be activated (i.e., booted-up). Whenthe decision 402 determines that a software start-up request has notbeen issued, then the software start-up request 402 awaits such arequest. Once the decision 402 determines that a software start-uprequest has been received, a battery level for a battery internal to theelectronic device is examined 404. Then, the battery level is compared406 with a first threshold level. A decision 408 then determines whetherthe battery level is adequate.

When the decision 408 determines that the battery level is inadequate,then a decision 410 determines whether a peripheral connection ispresent. When the decision 410 determines that a peripheral connectionis present, then the electronic device enters 412 a charge mode. In thecharge mode, the battery of the electronic device is charged by at leastpower supplied over the peripheral bus. Once the charge mode is entered412, a delay period is imposed 414. The delay period is associated withthe time period during which the battery of the electronic device isconstantly charged. Thereafter, the battery level is again examined 416.Then, the battery level is compared 418 with a second threshold level.The second threshold level can be the same or different than the firstthreshold level. In examining the battery level, charging of the batteryis known to affect the measured battery level. Hence, in one embodiment,the charging is stopped while the battery level is examined, and inanother embodiment, the charging is not stopped but the second thresholdlevel is adjusted to offset for the effects of the charging.

Following the comparison 418 of the battery level with the secondthreshold level, a decision 420 determines whether the battery level isadequate. When the decision 420 determines that the battery level isadequate, then the charge mode is exited 422. When the charge mode isexited, the charging of the battery stops (at least until start-up hascompleted). Alternatively, when the decision 420 determines that thebattery level is inadequate, then the start-up process 400 remains inthe charge mode so that the battery can be further charged during atleast the delay period being imposed 414.

On the other hand, when the decision 410 determines that a peripheralconnection is not present, then a low power indication can be displayed424 on a display screen associated with the display device. As anexample, the low power indication can be text or graphics that are usedto signal to a user of the electronic device that the electronic deviceshould be coupled to an external power source. After the low powerindication has been displayed 424 for a period of time, the electronicdevice is then turned off 426. Here, the electronic device can be turnedoff because the only power available is from the battery and isinadequate to successfully perform start-up. Following the block 426,the start-up process 400 ends without having started-up the electronicdevice. Alternatively, in one embodiment, following the display 424 ofthe low power indication, a period of time can be provided for the userof the electronic device to cause connection to a power source (e.g.,peripheral bus) to be made, and then proceed to enter 412 the chargemode.

Following the block 422, the start-up process 400 returns again to FIG.4A where a full boot of the software residing on the electronic deviceis initiated 428. Also, when the decision 408 determines that thebattery level is adequate, a full boot of the software residing on theelectronic device is also initiated 428. As the boot-up is beingperformed, the battery level can be again examined and compared to athreshold level. A decision 430 can then determine whether the batterylevel is still adequate. Here, the full boot of the software has beeninitiated 428. Hence, the decision 430 is determining whether thebattery level is still adequate while the start-up (i.e., boot-up) ofthe software completes. When the decision 430 determines that thebattery level is still adequate, a decision 434 determines whether theboot-up has completed. When the decision 434 determines that the boot-uphas not yet completed, the start-up process returns to repeat theoperation 428 and subsequent operations so that boot-up can complete.Alternatively, when the decision 430 determines that the battery levelis now inadequate, the full boot of the software is cancelled 432.Following the block 432, the start-up process 400 proceeds to thedecision 410 and subsequent operations as illustrated in FIG. 4C so thatthe battery can be charged. However, it is possible that the decision420 in this instance would require that the battery level be higher thana previous attempt to charge the battery given that the battery levelbecame inadequate during boot-up.

In any event, when the decision 434 determines that the boot-up (orstart-up) has completed, a decision 436 determines whether a peripheralconnection is present. When the decision 436 determines that aperipheral connection is provided, the electronic device negotiates 438for enhanced peripheral power. Here, the peripheral connection providespower to the electronic device via the peripheral bus. In oneembodiment, the limit on the power that can be drawn from the peripheralbus is substantially limited. However, typically, the peripheral busessupport greater demands of power but require that the peripheral device(i.e., electronic device) negotiate with the host computer supplying theperipheral bus to obtain additional peripheral power. For example, theUSB specification places a limit on power drawn from the USB but permitsa higher limit following a negotiation process.

Following the negotiation 438, a decision 440 determines whether thenegotiation was successful. When the decision 440 determines that thenegotiation was successful, then the electronic device is operated 442in an enhanced power mode. While in the enhanced power mode, the batterycan be further charged as needed. On the other hand, when the decision440 determines that negotiation was not successful, or when the decision436 determines that no peripheral connection is available, then theelectronic device is operated 444 in a low power mode. In oneembodiment, the presence of a low battery level together with the lackof either a peripheral connection or a power adapter connection wouldcause the electronic device to be shut-down if required to operate inthe low power mode.

FIG. 5 is a block diagram of a media player 500 according to oneembodiment of the invention. The media player 500 includes a processor502 that pertains to a microprocessor or controller for controlling theoverall operation of the media player 500. The media player 500 storesmedia data pertaining to media items in a file system 504 and a cache506. The file system 504 is, typically, a storage disk or a plurality ofdisks (e.g., hard disk drives(s)). The file system 504 typicallyprovides high capacity storage capability for the media player 500.However, since the access time to the file system 504 is relativelyslow, the media player 500 can also include a cache 506. The cache 506is, for example, Random-Access Memory (RAM) provided by semiconductormemory. The relative access time to the cache 506 is substantiallyshorter than for the file system 504. However, the cache 506 does nothave the large storage capacity of the file system 504. Further, thefile system 504, when active, consumes more power than does the cache506. The power consumption is often a concern when the media player 500is a portable media player that is powered by a battery 507 orperipheral bus. The media player 500 also includes a RAM 520 and aRead-Only Memory (ROM) 522. The ROM 522 can store programs, utilities orprocesses to be executed in a non-volatile manner. The RAM 520 providesvolatile data storage, such as for the cache 506.

The media player 500 also includes a user input device 508 that allows auser of the media player 500 to interact with the media player 500. Forexample, the user input device 508 can take a variety of forms, such asa button, keypad, dial, etc. Still further, the media player 500includes a display 510 (screen display) that can be controlled by theprocessor 502 to display information to the user. A data bus 511 canfacilitate data transfer between at least the file system 504, the cache506, the processor 502, and the CODEC 512.

In one embodiment, the media player 500 serves to store a plurality ofmedia items (e.g., songs) in the file system 504. When a user desires tohave the media player play a particular media item, a list of availablemedia items is displayed on the display 510. Then, using the user inputdevice 508, a user can select one of the available media items. Theprocessor 502, upon receiving a selection of a particular media item,supplies the media data (e.g., audio file) for the particular media itemto a coder/decoder (CODEC) 512. The CODEC 512 then produces analogoutput signals for a speaker 514. The speaker 514 can be a speakerinternal to the media player 500 or external to the media player 500.For example, headphones or earphones that connect to the media player500 would be considered an external speaker.

The media player 500 also includes a network/bus interface 516 thatcouples to a peripheral bus 518. The peripheral bus 518 allows the mediaplayer 500 to couple to a host computer. The peripheral bus 518 can alsoprovide power to the media player 500. A power controller and batterycharger 520 receives power from the peripheral bus 518 (if connected)and the battery 507 and outputs an output power POUT for power the powerconsuming circuitry of the media player 500. The power controller andbattery charger 520 can also monitor battery level and charge thebattery 506. The processor 502 can also communicate with the powercontroller and battery charger 520 so as to determine when to completestart-up, negotiate for enhanced peripheral power, etc.

The media items discussed herein are not limited to audio items (e.g.,audio files or songs). For example, the media item can alternativelypertain to videos (e.g., movies) or images (e.g., photos).

The various aspects, embodiments, implementations or features of theinvention can be used separately or in any combination.

The invention is preferably implemented by hardware and software, butcan also be implemented in hardware or software. The invention can alsobe embodied as computer readable code on a computer readable medium. Thecomputer readable medium is any data storage device that can store datawhich can thereafter be read by a computer system. Examples of thecomputer readable medium include read-only memory, random-access memory,CD-ROMs, DVDs, magnetic tape, optical data storage devices, and carrierwaves. The computer readable medium can also be distributed overnetwork-coupled computer systems so that the computer readable code isstored and executed in a distributed fashion.

The advantages of the invention are numerous. Different aspects,embodiments or implementations may yield one or more of the followingadvantages. One advantage of the invention is that a portable electronicdevice can be started from a dead battery using power provided over apower-limited peripheral bus. Another advantage of the invention is thatstart-up of a portable electronic device can be achieved using powerfrom a power-limited peripheral bus together with power from a batteryof the portable electronic device. Another advantage of the invention isthat a substantially depleted battery of a portable electronic devicecan be initially charged so that operation (e.g., start-up) of theportable electronic device can be thereafter achieved without exceedinglimits on power to be drawn from a peripheral bus. Still anotheradvantage of the invention is that operation (e.g., start-up) of aportable media device can be reliably performed even when a battery issubstantially depleted.

The many features and advantages of the present invention are apparentfrom the written description and, thus, it is intended by the appendedclaims to cover all such features and advantages of the invention.Further, since numerous modifications and changes will readily occur tothose skilled in the art, the invention should not be limited to theexact construction and operation as illustrated and described. Hence,all suitable modifications and equivalents may be resorted to as fallingwithin the scope of the invention.

1. A method for managing power in a battery powered portable electronicdevice having a battery, comprising: receiving a request to initiate apower intensive operation that consumes power at least in part from thebattery; checking a battery level before initiating execution of thepower intensive operation; initiating execution of the power intensiveoperation, performed by power consuming circuitry in the battery poweredportable electronic device, when the battery level is greater than afirst threshold level; checking the battery level during execution ofthe power intensive operation; canceling execution of the powerintensive operation before completing the power intensive operation,when the battery level is not sufficient to successfully completeexecution of the power intensive operation; after canceling execution ofthe power intensive operation and when the portable electronic device iscoupled to an external power source, charging the battery from theexternal power source until the battery level is greater than a secondthreshold level, the second threshold level being higher than the firstthreshold level; and re-initiating from the beginning execution of thepower intensive operation after charging the battery to greater than thesecond threshold level.
 2. The method as recited in claim 1, furthercomprising: shutting down the portable electronic device after the powerintensive operation is cancelled when the portable electronic device isnot connected to the external power source.
 3. The method as recited inclaim 2, wherein the external power source is connected to the batterypowered portable electronic device by way of a peripheral bus havingdata and power lines.
 4. The method as recited in claim 3 wherein aplurality of power levels can be provided over the peripheral bus to theportable electronic device.
 5. The method as recited in claim 4 whereinsaid method further comprises: negotiating for a higher power level ofthe plurality of power levels provided to the portable electronicdevice.
 6. The method as recited in claim 1, wherein the portableelectronic device includes a display screen, and wherein said methodfurther comprises: displaying a low power indication on the displayscreen while the battery level is less than the second threshold.
 7. Themethod as recited in claim 1, wherein the portable electronic device isa portable media player having a data storage device that stores mediaitems.
 8. The method as recited in claim 1, wherein the portableelectronic device is a mobile telephone or a personal digital assistant.9. A power manager system included in a battery powered electronicdevice having a battery, comprising: a battery monitor coupled to thebattery arranged to determine a battery level of the battery; and aprocessor coupled to the battery monitor arranged to: initiate a powerintensive operation, which consumes power at least in part from thebattery, performed by power consuming circuitry in the battery poweredelectronic device when the battery monitor determines that the batterylevel is greater than a first threshold value before initiatingexecution of the power intensive operation, periodically check thebattery level during execution of the power intensive operation, cancelexecution of the power intensive operation before completing the powerintensive operation, when the battery level is not sufficient tosuccessfully complete execution of the power intensive operation, andwhen the portable electronic device is connected to an external powersource, charge the battery until the battery level is greater than asecond threshold value, the second threshold value being higher than thefirst threshold value, and re-initiate from the beginning execution ofthe power intensive operation after charging the battery to greater thanthe second threshold value, otherwise post a notification of a low powerindication, and shut down the portable electronic device.
 10. The powermanager system as recited in claim 9 wherein the power manager system iscoupled to the external power source that provides at least the power tocharge the battery by way of a peripheral bus.
 11. The power managersystem as recited in claim 10, wherein the external power source isarranged to provide a plurality of power levels and wherein theprocessor is arranged to negotiate for a higher power level.
 12. Thepower manager system as recited in claim 11 wherein when the processornegotiates the higher power level and the power intensive operation isdelayed, then the power manager commences the power intensive operationregardless of the battery level of the battery.
 13. The power managersystem as recited in claim 9, wherein the portable electronic deviceincludes a display screen, and wherein the low power indication isdisplayed on the display screen when the power intensive operation isdelayed.
 14. The power manager system as recited in claim 9, wherein theportable electronic device is a portable media player having a datastorage device that stores media items.
 15. The power manager system asrecited in claim 9, wherein the portable electronic device is a mobiletelephone or a personal digital assistant.
 16. A portable media playercomprising: a battery; a processor; a media store for storing mediaitems; a communication interface for interfacing with a host devicehaving an external power source via a cable that provides media data andpower to the portable media player when the cable is connected betweenthe media player and the host device; and a power manager for managingpower in the portable media player, said power manager comprising: abattery monitor coupled to the battery and the processor arranged todetermine a battery level of the battery, wherein when the processor:initiates execution of a power intensive operation, which consumes powerat least in part from the battery, performed by power consumingcircuitry in the portable media player, when the battery monitordetermines that the battery level is greater than a first thresholdvalue before execution of the power intensive operation, periodicallychecks the battery level during execution of the power intensiveoperation, cancels execution of the power intensive operation beforecompleting the power intensive operation when the battery level is notsufficient to successfully complete execution of the power intensiveoperation, and when the portable media player is connected to theexternal power source, charges the battery until the battery level isgreater than a second threshold value, the second threshold value beinghigher than the first threshold value, and re-initiates from thebeginning execution of the power intensive operation after charging thebattery to greater than the second threshold value, otherwise posts anotification of a low power indication, and shuts down the portablemedia player.
 17. The portable media player as recited in claim 16wherein the cable is a peripheral bus having data and power lines. 18.The portable media player as recited in claim 17 wherein a plurality ofpower levels may be provided over the peripheral bus to the portableelectronic device.
 19. The portable media player as recited in claim 18wherein the processor negotiates for a higher power level of theplurality of power levels provided to the portable electronic device,wherein if the higher power level is sufficient to perform thepower-intensive operation, the power intensive operation is performedand not delayed.
 20. The portable media player as recited in claim 16,wherein the portable electronic device includes a display screenarranged to display a low power indication on the display screen whilethe power intensive operation is delayed.
 21. The portable media playeras recited in claim 16, wherein the portable electronic device is aportable media player having a data storage device that stores mediaitems.
 22. The portable media player as recited in claim 16, wherein theportable electronic device is a mobile telephone or a personal digitalassistant.
 23. A non-transitory computer readable medium for storing acomputer program executable by a processor for managing power in abattery powered portable electronic device having a battery, saidcomputer program comprising: computer code for receiving a request toinitiate a power intensive operation that consumes power at least inpart from the battery; computer code for checking a battery level beforeinitiating execution of the power intensive operation; computer code forinitiating execution of the power intensive operation, performed bypower consuming circuitry in the battery powered portable electronicdevice, when the battery level is greater than a first threshold level;computer code for checking the battery level during execution of thepower intensive operation; computer code for canceling execution of thepower intensive operation before completing the power intensiveoperation when the battery level is not sufficient to successfullycomplete execution of the power intensive operation; after cancelingexecution of the power intensive operation, computer code for chargingthe battery until the battery level is greater than a second thresholdlevel, the second threshold level being higher than the first thresholdlevel, when the portable electronic device is coupled to an externalpower source; and computer code for re-initiating from the beginningexecution of the power intensive operation after charging the battery togreater than the second threshold level.
 24. The computer program asrecited in claim 23 wherein the external power source is connected tothe battery powered portable electronic device by way of a peripheralbus having data and power lines.